In the 1930s Polish military authorities constructed a number of fortifications in the area of Sarny, known as Sarny Fortified Area (Sarnenski Rejon Umocniony), along the Sluch river.

After the Soviet invasion of Poland in September 1939 Sarny became a concentration point for units under command of gen. bryg.Wilhelm Orlik-Rückemann. Concentraction was taking place under cover of "Sarny" regiment commanded by ppłk. Nikodem Sulik. The regiment itself was stemming the attack of the Soviet 60th Rifle Division based on strong fortifications of Sarny Fortified Area. Crew of a single bunker, under command of ppor. Jan Bołbot, lasted out in its position up to 19 September, delaying advance of Soviet units.[1] Some of the bunkers making up this line still exist.